Philips LCD 42PFL5432D/37 - Bad PSU

**momaka** · 02-22-2011, 10:26 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Originally posted by nuklear

and this is what i seen in the "spare parts list" IC907 9965 000 43345 TEA1507P/N1.

Perfect! I got IC907 down as TEA1507P (this is the PWM controller for the standby circuit).

Now the only thing I couldn't read from the schematic is the output voltages. It looks like it says 21 volts for the top and 12 volts for the bottom one - these voltage are all the way on the right on the schematic. Please verify that the values I read are correct.

So, it looks like the external standby PSU mod will work. Just need to get the value of the standby voltage, remove a few jumpers, wire the external PSU, and it will be good to go.

As for trying to fix the PSU by reusing a transformer from another PSU, it probably won't be possible, unfortunately. The old transformer has 2 auxiliary windings while most computer PSUs only have 1. Save the old transformer in your junk box, though, just in case you run into another transformer with a similar core.

**thelmores** · 02-23-2011, 07:35 AM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

And ALWAYS make sure you get 105c (or higher) rated caps......

Some manufacturers will try to get away with 85c caps, and they will not last nearly as long as a good 105c rated caps.

105c caps are also rated for lifetime, whether it be 1000hrs, 2000hrs, 3000hrs, etc.
You want to choose the best caps you can, while at the same time keeping the price reasonable.

**nuklear** · 02-25-2011, 09:32 AM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

it looks to me likke 24 and 12 if I am reading it right.

Attached Files

**PlainBill** · 02-25-2011, 01:10 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Originally posted by nuklear

it looks to me likke 24 and 12 if I am reading it right.

Probably not. That appears to be the output of the main section of the supply, you need the standby section.

PlainBill

**nuklear** · 02-25-2011, 10:03 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

ok this might be it.

Attached Files

**PlainBill** · 02-25-2011, 10:25 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Originally posted by nuklear

ok this might be it.

It's hard to tell when working with fragments of schematics, but there are clues. Notice that the defective transformer is T904. T904 is the transformer for the 12V output. The STANDBY line is coming from the main board, and controls the SMPS controller for the 24V supply. So the Standby supply is 12V.

PlainBill

**momaka** · 02-25-2011, 11:28 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Originally posted by PlainBill

So the Standby supply is 12V.

I concur.
The other clue that gives this away is that there's only 2 transformers in this power supply (one of them being the broken one you mentioned) and each has a single output only.

So what's next?...
Remove J5 and R974. This will disable the primary side of the standby circuit. Then finally wire in 12v from an external power supply (see attached image below). Note that ground (GND) from the external PSU also needs to be connected.
I suggest a PSU capable of at least 2A. Also if there's any loose solder like in the pictures you posted, make sure to clean it up.

Attached Files

**nuklear** · 02-28-2011, 08:52 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

so where do I get this psu to put onto this board? Is this something I can do with having no experience in doing this kind of repair?

**momaka** · 03-01-2011, 10:34 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Originally posted by nuklear

Is this something I can do with having no experience in doing this kind of repair?

Most likely yes.
The wiring part is pretty straightforward - it's like putting new batteries in your remote. The only difference is there is some soldering involved (think of it as if the batteries had wires that you needed to connect). If you've never done any soldering before, that's the only part of this job that might make it a bit more challenging. But soldering is not all that hard. I've seen a quite a few people here come with no experience and recap their monitors. Just read the FAQs or see some videos on YouTube on how to solder.
Also:
1) make sure your soldering iron nice and hot before you solder/desolder
2) put a little solder on the tip of the iron before soldering/desodering components - this will allow for better heat transfer
3) don't be afraid that you might "burn" the board - keeping the iron on the board for up to 5-8 seconds is acceptable. It's much worse to try to remove or solder a component when you're not heating it enough.

----
What you need to do for this repair is:
1) desolder/remove jumper wire J5 and resistor R974 from the board.
2) take the (+) wire from the 12v external PSU and connect it to any of the two pins circled in red in the picture above.
3) take the (-) wire from the 12v external PSU and connect it to any of the two pins circled in black (this is also the ground of the power supply).
4) remove any loose solder from the board

Now the question is, have you found a 12v adapter/power supply yet?
If you want, you can just temporarily use a computer PSU to see if the TV will come on. On a computer PSU, 12v is carried by the yellow wires. The black wires are ground.

Again, the only downside of this mod is that it won't look too pretty, mainly because you will need to have both the external power supply and the TV plugged in order for the TV to work. And if you don't have an external power supply yet, it's probably a better idea to buy a new PSU for the monitor than to waste money on buying an external power supply.

**nuklear** · 03-02-2011, 12:34 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

It worked! Thanks alot! Only thing now is I get a blinking/flashing from the tv. just to make sure, I used a power cord that had a 12v output is that ok to use? any ideas of why it would be flashing mybe every second would be great. Ok it stopped flashing mybe had to warm up? But again Thanks alot!!! saved alot of money and I appreciate it and so does my son!

**nuklear** · 03-02-2011, 04:06 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

hmmm... Resoldered it and now tv wont turn on? I just re ran the wires so i could put the back on and now it doesnt even have the standby light on again lol

**nuklear** · 03-02-2011, 04:39 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

well thanks to everyone that helped I figured out the wireing prob and broke the lcd screen while putting the back back on, so looks like its ment to stay broken

**Dizzer** · 03-06-2011, 09:49 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

I too have the same exact problem as the TC. I have ordered the caps and will post my results upon installation of the new caps. For me, both caps B and D (based off the image in the first post) were bulging. I am replacing all of them just in case.

**trixter** · 03-28-2011, 02:21 AM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Working on the same case. Just opened the tv and the caps on psu were buldging. Same values as the ones posted in first thread. Once caps A,B,C, and D come in, I'll solder them in and see results. The tv is now doing that chirping sound with no screen. I've fixed quit a few things in my time. Hopefully I'll add this on to the list.

**trixter** · 04-01-2011, 01:49 AM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Just replaced ABCD and still chirps. Next I'll try all the small caps and see.

Does my T905 Transformer look bad. It sounds like the chirping is coming from this. It looks this way on both sides.

Attached Files

**momaka** · 04-01-2011, 04:29 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Originally posted by trixter

Does my T905 Transformer look bad.

Hard to say exactly. Looks fine to me. Check the solder joints on the other side - i.e. see if any of them look dry or cracked. Also, change the small electrolytic caps like you mentioned and let us know if the problem remains.

**trixter** · 04-02-2011, 11:22 AM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Yes the transformer does look good. I meant the solder. Looks like they're kinda burnt. That's all.

**momaka** · 04-02-2011, 11:21 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

That's likely left over flux from when the transformer was soldered at the factory. Did you replace the small caps yet? Also did you try measuring the standby voltage at connector CN902 (the one next to capacitor C955)? There should be 12v there when the PSU is working properly.

**trixter** · 04-02-2011, 11:57 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

Can I test the voltage without the TV? I don't have the TV now. Just the powerboard. I can plug it into the power but I'm sure it won't turn on without something jumping certain pins.

Attached is where I noticed some discoloration under two diodes. I took the diodes out and tested with DMM on diode mode. I get a reading both ways on both diodes. I believe that means they are bad. I'll get them replaced. They are part# P6KE120A. Data sheet says they are uni directional.

Has anyone ever fixed their board? Seems no one has actually fixed their but just has advice.

Attached Files

**Dgtech** · 04-03-2011, 04:12 PM

Re: Philips LCD 42PFL5432D/37 - Bad PSU

What type of reading do you get both ways? Is it 0 ohms both ways? Using the diode test, what voltage reading do you get both ways, anode to cathode, cathode to anode?

Philips LCD 42PFL5432D/37 - Bad PSU

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